1. Field of the Invention
An aspect of the present invention relates to a multi-layered optical recording medium, a method of assigning an address in a multi-layered optical recording medium, a reproducing apparatus, a reproducing method, and a recording method, thereof.
2. Description of the Related Art
FIG. 1 is a diagram illustrating a sector structure on an optical recording medium according to conventional technology. Generally, an optical recording medium has one- or two-layer recording surfaces. In each recording layer, a spiral track is formed, and the track is divided into a plurality of sectors. Each sector has a storage capacity, such as 512 bytes or 2048 bytes, and is used as a data recording unit.
In order to maximize the storage capacity of an optical recording medium, the recording density of the optical recording medium is made to be constant across the whole disk surface, and to do so, all sectors, as illustrated in FIG. 1, have identical sizes. Also, in order to guarantee that a predetermined amount of data is reproduced in a unit of time, the disk is driven by a constant linear velocity (CLV) control. According to the CLV control, the disk is rotated at a variable velocity with respect to the radial position on the disk of an optical head projecting a beam spot that converges on the disk during a predetermined interval in a unit of time.
FIG. 2A is a diagram illustrating a sector structure of an optical recording medium such as a digital versatile disk (DVD) in particular, according to conventional technology. Each sector of the DVD includes a header in which an address for identifying a sector is recorded, a data block in which user data is recorded, and an error correction code (ECC) in which a code to be used for correcting an error during reproduction of data is recorded.
FIG. 2B is a diagram illustrating a recording area structure of an optical recording medium such as a Blue-ray disk (BD) in particular, according to conventional technology. Referring to FIG. 2B, the optical recording medium can be divided into three parts including a lead-in area, a data area and a lead-out area. In particular, the data area is composed of a user data area in which actual user data is recorded, and a spare area, which is used to replace a defective area in the user data area. The spare area is composed of an inner spare area (ISA) positioned on an inner circumference of the data area, and an outer spare area (OSA) positioned on an outer circumference of the data area.
In the recording area structure of a BD, formed as illustrated in FIG. 2B, data is recorded on units of clusters in all areas of the data area, and in particular, each cluster is further divided into a plurality of recording units. This recording unit is referred to as a ‘sector’. In each cluster, a plurality of sectors are disposed, and an address unit number (AUN) is given to each two sectors.
Methods of increasing a storage capacity in an optical recording medium include a method of using a laser with a shorter wavelength in order to increase recording and reproducing density, and a method of building multiple layers on one disk. Current optical recording media usually have one or two recording layers, however, in order to increase a storage capacity of current optical recording media, a disk having a plurality of recording layers can be considered. In a multi-layered optical recording medium, assignment of addresses is important since an address should be unique in an optical recording medium, and address information requires a storage space separate from data. The smaller the size of the address information, the wider the storage space required for storing data.
FIG. 3A is a diagram illustrating an example of assigning a sector address on a multi-layered optical recording medium according to conventional technology. Information on an address assigned on a multi-layered optical recording medium includes a layer address indicating a layer number, and a sector address indicating the address of a sector. A layer address is identical in relation to one layer, and a different value is assigned as a sector address to each sector. FIG. 3A illustrates the sector address of an optical recording medium having 4 recording layers (L1, L2, L3, and L4). On an identical radial position of different layers, the sector address of each recording layer is identical. For each recording layers, on a radial position of Rin, Rout and R, a sector address is Xin, Xout and X respectively. In this case, since an identical sector address appears in each layer, it is possible that data of a different layer be reproduced using the same sector address.
FIG. 3B is a diagram illustrating another example of assigning a sector address on a multi-layered optical recording medium according to conventional technology. Referring to FIG. 3B, recording layers of an optical recording medium are divided into odd-numbered layers and even-numbered layers. Sector addresses are assigned such that sector addresses in all the odd-numbered layers are identical to each other and sector addresses in all the even-numbered layers are identical to each other. Also, sector addresses are assigned such that a sector address of an odd-numbered layer is a complement of a sector address of an even-numbered layer. In this case, even if addresses of the odd-numbered layers and the even-numbered layers are different from each other, data in the different layers can be reproduced because of the assigning of the complement addresses.